Metal storage bins and the like are generally of a factory prefabricated construction with the parts thereof shipped for assembly in the field. Usually, erection of the bin side wall structure requires special personnel and equipment and separate fastenings for securing the prefabricated sections together. As a result, this type of bin is relatively expensive to manufacture and transport and requires appreciable time in the field for installation or erection.
Thus, U.S. Pat. No. 2,751,672 discloses a storage bin having a sidewall structure comprised of a series of helical or spiral strips that are factory prefabricated and specially designed for strength to withstand a working stress at a particular height location on the side wall. Although the storage bin is erected in the field, the prefabricated parts must be assembled in a predetermined overlapping pattern by special erecting equipment and with the parts then being connected together by separately provided bolt means, after which the connecting joints are calked or sealed. The roof unit is also prefabricated for erection in the field and is assembled as a unit with the wall structure.
The disclosure of U.S. Pat. No. 4,067,097 is also directed to a cylindrical bin formed of factory fabricated helical units assembled in the field and secured together by weldments.
In U.S. Pat. No. 3,380,147, the side wall structure is of a cylindrical shape and erected in the field by passing a roll of sheet steel through a set of crimping rollers to slightly curve the sheet along with off-setting the upper edge of the sheet so that a leading section of the sheet will receive the lower edge of an adjacent trailing section of the sheet as the sheet is being helically wound. These adjacent edges are initially spot welded against separation and then finally secured by a continuous weld. Preformed strips of the sheet roll are secured at the top and bottom of the side wall structure to provide horizontal end surfaces for mounting of the roof unit on the upper end of the side wall, and for the support of the bottom end of the side wall on a foundation. Upright beam members, that are circumferentially spaced about and welded to the side wall structure after it has been helically wound, assist in the lowering of the erected wall structure onto the foundation therefor. Additionally, these beam members remain secured to the side wall and function as reinforcing members for resisting side wall expansion.